GEOLOGICAL OBSERVATIONS 



definitely ascertained by us. It was at least 20 ft., pos- 

 sibly as much as 30 ft., above the sea. 



The evidence generally of these raised beaches is very 

 interesting, as showing the probability that when the ice, 

 in recent geological time, had its maximum extension in 

 this region, there was probably a subsidence, possibly due 

 to the load, on this part of the earth's crust, of such a vast 

 extra thickness of ice, and that after the subsidence, which 

 probably lagged behind the epoch of maximum glaciation, 

 there has been a gradual re-emergence to the amount of 

 150 to 200 ft. The brachiopod and polyzoon in the 

 raised marine mud from the Larsen area have kindly been 

 identified for us by Mr. C. Hedley and Mr. E. F. Hallman 

 respectively, of the Australian Museum. 



Peat Deposits 



Aanongst formations of recent origin may be men- 

 tioned peat. A deposit of peat was discovered by one 

 of us formed on the bottom of the lake called Coast Lake. 



This peat is formed from the remains of a large 

 fungoid plant, which grows in profusion in the water of 

 these coastal lakes when the ice thaws in midsummer. 



A deposit of mirabilite was discovered by one 

 of us at the spot shown on the map near Cape 

 Bame, after the summer thaw had set in. The 

 white colour of the salt during winter rendered it in- 

 distinguishable from the surrounding snow, but after 

 the thaw the difference of course was noticeable between 

 this white salt and the edges of the dark volcanic rock. 



Apparently this mirabilite forms one of the products 

 of evaporation of an old lake. Numbers of these dried 

 lake basins were noticed by us amongst the glacial 

 moraines on these western slopes of Erebus near Cape 

 Barne and our winter quarters. 



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